[Pw_forum] Constraints

[yuva rani]

Thank you sir. But I did not get clear idea about FLAGS. So please
could you attach me the example file using constraints.

Thanks in advance

On 6/14/11, m.g.p.krishna at chem.leidenuniv.nl
<m.g.p.krishna at chem.leidenuniv.nl> wrote:
> yuva: there are some quick answer...
>
> Relaxation:
> you can use FLAGS in atoms to relax/not relax in a particular
> Cartesian direction.
> example:
> Al     11.039040    5.580000   24.296861   0 0 1,
> means that Aluminium is fixed EXCEPT in the Z direction. So it will
> relax on Z direction. In your case I suggest to use this kind of
> relaxation for every atom with a fixed Constraint on bond lengths (see
> previous posts of mine).
>
> KPoints: I, generally, use 'automatic' K points which is a kind of
> Monkhorst-Pack grid (more genereic). Suppose you have orthorhombic
> cell (a,b,c) where the magnitudes are (a=b < c), then I will use more
> Kpoints in a and b direction and less kpoints in c direction. Since
> Kpoints are defined in the reciprocal space (say, a'b'c' where
> magnitudes are a'b' > c'), you should use more k points to span the
> necessery irrep. areas in that reciproal space of a'b'c'.
> simply You can start with (see manual)
>   K_POINTS automatic
>    nx ny nz shiftx shifty shifty
>
> It is a good idea to visualize your supercell prior to put some values
> in nx,...
>
>
> By the way why you are using a BASH script? It was in QE package just
> to make tests quite smoothly/interactively. So pls use a simple *.in
> file which contains the input-data BETWEEN cat > alpen148.rx.in << EOF
> to EOF (bottom, near to Kpoints...)
>
> good luck
>
> Krishna Mohan GP
> Center for Superfunctional Materials
> POSTECH
> Sotuh Korea.
>
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>